1. Field of the Invention
The present invention relates in general to an ink-jet printing device, and more particularly to a platen of the ink-jet printing device.
2. Description of Related Art
The ink-jet printing device includes a printing head having nozzles through which droplets of an ink are selectively ejected toward a recording medium such as a sheet of paper, to print desired characters or any other images on the recording medium. The ink-jet printing device further includes an inkjet printing platen (hereinafter referred to simply as “platen”, where appropriate) which is disposed in an opposed relationship with the printing head, to support the recording medium such that the recording medium faces the printing head. In operation of the ink-jet printing device, the printing head ejects the ink droplets from the selected nozzles while the printing head is reciprocated in the width direction of the recording medium.
The ink-jet printing device may be operated to perform a so-called “non-margin printing operation” on a photographic sheet or postcard. In the non-margin printing operation, an image is printed on the recording medium, without a margin left along an edge of the recording medium. For example, an image is printed over the entire length of the recording medium, without the top and bottom margins left along the leading and trailing edges of the recording surface of the recording medium. In this non-margin printing operation, the ink droplets are ejected from the printing head toward not only the edge portions of the recording medium, but also areas outside the recording surface of the recording medium, so that the ink droplets are deposited on areas of the upper surface of the platen which are outside the recording medium, for instance, which are ahead of the leading edge of the recording medium and behind the trailing edge of the recording medium. The ink droplets deposited on the platen may cause contamination of the back surface of the following recording medium which is fed next onto the platen.
As one solution to the above-indicated problem of contamination of the recording medium with the ink droplets deposited on the platen, JP-2006-205697A discloses a platen that is provided with an ink-receiver portion in the form of a succession of V-grooves formed in its upper surface. The V-grooves permit the ink deposited on the platen to flow to a desired location, owing to a capillarity action and/or an effect of inclination of the V-grooves. For instance, the V-grooves communicate with an ink absorbing member so that the ink flows through the V-grooves to the ink absorbing member and is absorbed into the ink absorbing member, whereby the ink deposited on the platen can be removed from the platen.
JP-2006-224505A discloses a platen having contact members each of which is held in contact with inner surfaces of the corresponding one of grooves formed in the upper surface of the platen, such that the contact member and the groove cooperate to define a predetermined gap serving as an ink flow passage through which an ink deposited on the platen is discharged from the platen, owing to the capillarity action of the ink flow passage.
JP-2003-200587A discloses an ink-jet printing device provided with an ink reservoir in which a plurality of thin sheets are arranged in a spaced-apart relation with each other, to define a plurality of ink flow passages, so that an ink in the ink reservoir is directed toward an outlet of the ink reservoir, owing to a capillarity action of the ink flow passages.
JP-2005-283959A discloses an optical fiber array wherein projections are formed between two substrates and optical fibers interposed therebetween, so as to define gaps having a capillarity action.
The amount of ink droplets deposited per unit time on the platen of an inkjet printing device in the non-margin printing operation tends to increase with an increase of the printing speed of the device. Accordingly, it is desired to increase the capacity of the ink-jet printing device to remove the ink deposited on the platen.
It is generally known that the capillarity action of a flow passage increases with a decrease of the cross sectional surface area of the flow passage. For example, the capillarity action of the flow passages between thin sheets disclosed in JP-2003-200587A and the gaps defined by the projections disclosed in JP-2005-283959A increases with an increase of the cross sectional surface areas of the flow passages and gaps. Therefore, the capillarity action of the V-grooves disclosed in JP-2006-205697A can be increased by either reducing the width of the V-grooves, or increasing the depth of the V-grooves to reduce the angle of the V-grooves.
However, the reduction of the width of the V-grooves makes it difficult to form the platen, and reduces the amount of ink that can be temporarily accommodated in the V-grooves, giving rise to a risk of overflow of the ink. On the other hand, the increase of the depth of the V-grooves results in an increase of a distance between the printing head to the bottom of the V-grooves, giving rise to a risk of a failure of the ink droplets to be introduced into the V-grooves, with a result of floating and misting of the ink droplets. The ink mist tends to adhere to the components built in the ink-jet printing device, and to the recording medium on which a printing operation is to be performed, so that the quality of printing may be deteriorated, and the components of the device may be contaminated with the ink.